Running yarn is subjected to a heating operation in several different types of textile machines, such as a yarn texturing machine of the false twist type. In this type of machine, a series of adjacent false twist stations is provided along each side of the machine and the yarn is heated as it passes through an elongated slot or track in a heater element at each station. The yarn is usually provided with a coating or application of size, lubricant or the like, and when subjected to the heating operation, the coating material is partially evaporated and/or softened so that some of the coating material is removed and accumulated deposits build up on the sidewalls and bottom of the slot. In many instances these deposits build up to an amount sufficient to change the amount of heat applied to the yarn and may change the tension in the yarn. This change in tension or change in friction against the yarn can change the dye affinity of the yarn. Also, these deposits may be dislodged and integrated in the yarn passing along the slot. In addition, certain deposits harden and tend to nick or tenderize the yarn and in extreme cases will even break the strand of yarn.
Textile machines of this type must be periodically stopped and the heater blocks allowed to cool before the yarn heater slots can be cleaned. This cleaning operation usually includes manually scraping each slot with a brass probe, a metal brush or the like, applying a cleaning fluid, and wiping with rags or the like. This is a slow and costly operation and can result in damage to the heater slots and/or nonuniform cleaning of adjacent slots. The cooling and reheating of the heater blocks can also decrease the life of the heater blocks and waste energy.